Field of the Invention
The present invention relates to a breakdown voltage measuring method and a method for manufacturing a semiconductor device. More particularly, the present invention relates to a breakdown voltage measuring method capable of suppressing generation of an electric discharge during a measurement of a breakdown voltage and suppressing a residue of a foreign object on a cleaned semiconductor substrate, and to a method for manufacturing a semiconductor device to which the breakdown voltage measuring method is implemented.
Description of the Background Art
For a semiconductor device, particularly for a power semiconductor device, a breakdown voltage is one of significant properties. Therefore, in a method for manufacturing a semiconductor device, there is a case where a breakdown voltage of a semiconductor element formed in a semiconductor substrate is measured. When a condition for the measurement of the breakdown voltage is inappropriate, there is a case where a creeping discharge is generated from a measuring probe on the semiconductor substrate so that the semiconductor element is broken. Therefore, it would be necessary to suppress generation of the electric discharge during the measurement of the breakdown voltage to prevent the breaking of the semiconductor element.
As a method for preventing the breaking of the semiconductor element due to the electric discharge described above, there has been a known method of performing the measurement of the breakdown voltage of the semiconductor element with use of an insulating solution. For example, Japanese Patent Laying-Open No. 2003-100819 discloses a method of measuring the breakdown voltage of the semiconductor element in a state where the semiconductor element is immersed in the insulating solution. Moreover. WO2010/021070 discloses a method of measuring the breakdown voltage of the semiconductor element in a state where the insulating solution is applied to a surface of a part of the semiconductor substrate by potting.